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SUMMARY:Non-Gaussianity of superhorizon curvature perturbations beyond del
 ta N formalism - yuichi takamizu (DAMTP)
DTSTART:20140207T130000Z
DTEND:20140207T140000Z
UID:TALK50746@talks.cam.ac.uk
CONTACT:Helvi Witek
DESCRIPTION:We focus on the evolution of curvature perturbation on superho
 rizon scales by adopting the spatial gradient expansion and show that the 
 nonlinear theory\, called the beyond delta N-formalism as the next-leading
  order in the expansion. This formalism allows us to calculate the superho
 rizon evolution of a primordial non-Gaussianity beyond the so-called delta
  N formalism which is equivalent to leading order in the gradient expansio
 n.\nAs one application of our formalism for a single scalar field\, we can
  deal with the time evolution in contrast to delta N-formalism\, where cur
 vature perturbations remain just constant\, and nonlinear curvature pertur
 bation follows the simple master equation whose form is similar as one in 
 linear theory.  We review our formalism and discuss some application to pr
 imordial bispectrum generated by the effect of varying sound speed.  
LOCATION:Pavilion B Potter Room (B1.19)
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